Biotech company Amgen Inc. will lay off 200 manufacturing workers in Longmont and Boulder -- roughly a third of its Colorado workforce. Thousand Oaks, Calif.-based Amgen (Nasdaq: AMGN) had previously said it would close down its Colorado manufacturing operations for the anemia drug Epogen, which it plans to stop producing. Tony Kindelspire of the Longmont Times-Call reports that affected workers were notified Thursday that their jobs will end April 30.